If NaCl is doped with 10-4 mol % of SrCl2, the concentration of cation vacancies will be (NA = 6.023 x 1023 mol-1)                                                                             

(a) 6.023 x 1015 mol-1                                            (b) 6.023 x 1016 mol-1

(c) 6.023 x 1017 mol-1                                            (d) 6.023 x 1014 mol-1                                     

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Metals have conductivity of the order of (ohm-1 cm-1):-

(a)1012
(b)108
(c)102
(d)10-6

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A solid PQ have rock salt type structure in which Q atoms are at the corners of the unit cell. If the body centred atoms in all the units cells are missing, the resulting stoichiometry will be

(A) PQ

(B) PQ2

(C) P3Q4

(D) P4Q3

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Lithium borohydride (LiBH4), crystallises in an orthorhombic system with 4 molecules per unit cell. The unit cell dimensions are:- a = 6.81 Å , b = 4.43 Å ,c = 717 Å. If the molar mass of LiBH4 is
21.76 g mol-1.The density of the crystal is:-

(A) 0.668 gcm-3
(B) 0.585 gcm2
(C) 1.23 gcm-3

(D) None of these

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A solid has a bcc structure. If the distance of closest approach between the two atoms is 1.73Å . The edge length of the cell is:

(a) 200pm

(b) 32 pm

(c) 142.2 pm

(d) 2pm

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The anions (A) form hexagonal closest packing and atoms (C) occupy only 2/3 of octahedral voids in
it. then the general formula of the compound is-

(A) CA

(B) A2

(C) C2A3

(D) C3A2

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How many unit cells are present in a cube shaped ideal crystal of NaCl of mass 1.00g?

[ Atomic masses Na=23, Cl = 35.5]

(a) 2.57 x 1021

(b) 5.14 x 1021

(c) 1.28 x 1021

(d) 1.71 x 1021

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The most efficient packing of similar spheres is obtained in 

1. the simple cubic system and the body centered cubic system

2. the simple cubic system and the hexagonal close packed system

3. the face centered cubic system and the hexagonal close packed system

4. the body centered cubic system and the face centered cubic system

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In a compound, atoms of element Y form ccp lattice and those of element X occupy 2/3rd of tetrahedral voids. The formula of the compound will be :-

(a) X3Y4
(b)X4Y3
(c) X2Y3
(d) X2Y

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Close packing is maximum in the crystal lattice of:

(a) simple cubic
(b) face centred
(c) body centred
(d) none of these

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